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61.
The CD spectra of four filamentous bacteriophages--fd, IKe, Pf1, and Pf3--were analyzed to determine the alpha-helix contents of their major coat proteins. Measured spectra included the 192-nm band so that analyses could be carried out over the full wavelength range of the reference spectra for protein secondary structures available (a) from globular proteins [J.T. Yang, C.S.C. Wu, and H.M. Martinez (1986) Methods in Enzymology 130, 208-269] and (b) from poly(L-lysine) [N. Greenfield and G.D. Fasman (1960) Biochemistry 8, 4108-4116]. Extended analyses were also performed with the addition of the spectrum of a model beta-turn to the Greenfield and Fasman reference set, with the spectrum of a short alpha-helix in the Yang et al. reference set, and with an estimate of the spectrum of Trp added to both reference sets. The reference set based on the simple poly(L-lysine) polypeptide, plus a spectrum of a model beta-turn or of Trp, gave reasonably good fits to the measured spectra for all four phages and yielded the largest percentages of alpha-helix. The class I phages--fd and IKe--had large percentages of alpha-helix of 98 +/- 2 and 97 +/- 5%, respectively, while the two class II phages--Pf1 and Pf3--had similar but smaller alpha-helix contents of 83 +/- 6 and 84 +/- 2, respectively. While these alpha-helix contents were within the ranges previously reported from CD spectra of these phages in solution, they were more precise, and they indicated that the coat proteins of the intact phages have CD spectra that are probably modeled better by the reference spectra of polypeptides than by those of globular proteins. 相似文献
62.
Helical complexes formed between fd DNA and reductively methylated fd gene 5 protein were indistinguishable by electron microscopy from complexes formed with the nonmethylated protein. 13C NMR spectroscopy of 13C-enriched N epsilon, N epsilon-dimethyllsyl residues of the protein showed that three of these residues (Lys-24, Lys-46, and Lys-69) were selectively perturbed by binding of the oligomer d(pA)7. These were the same lysyl residues that we previously found to be most protected from methylation by binding of the protein to poly[r(U)] [Dick, L. R., Sherry, A. D., Newkirk, M. M., & Gray D. M. (1988) J. Biol. Chem. 263, 18864-18872]. Thus, these lysines are probably directly involved in the nucleic acid binding function of the protein. Negatively charged chelates of lanthanide ions were used to perturb the 13C NMR resonances of labeled lysyl and amino-terminal residues of the gene 5 protein. The terbium chelate was found to bind tightly (Ka approximately 10(5) M-1) to the protein with a stoichiometry of 1 chelate molecule per protein dimer. 13C resonances of Lys-24, Lys-46, and Lys-69 were maximally shifted by the terbium chelate and were maximally relaxed by the gadolinium chelate. Also, the terbium chelate was excluded by the oligomer d(pA)7. Computer fits of the induced chemical shifts of 13C resonances with those expected for various positions of the terbium chelate failed to yield a possible chelate binding site unless the chemical shift for Lys-24 was excluded from the fitting process.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
63.
M Hirasawa K A Gray M R Ondrias R W Larsen R W Shaw K J Morrow D B Knaff 《Biochimica et biophysica acta》1989,994(3):229-234
A recently discovered form of spinach catalase that contains both a novel heme and protoheme as prosthetic groups has been characterized using immunological and spectroscopic techniques. The enzyme appears to be a dimer of identical Mr 60,000 monomers. Extraction of the non-covalently bound prosthetic groups, followed by thin-layer chromatography of the extract, suggested that the novel heme contains four carboxylic acid side-chain groups. The resonance Raman spectrum of the resting enzyme indicates that the protoheme prosthetic group is five-coordinate and high-spin. The enzyme was shown to bind formate, azide and cyanide. Cyanide and azide binding to catalase are biphasic, suggesting the existence of two different binding sites for cyanide and azide in the enzyme. Results obtained from EPR and resonance Raman spectroscopies also support the hypothesis that two different ligand-binding sites are present in the enzyme. Western blots suggest that the Mr 60,000 peptide of the novel heme-containing catalase is similar or identical to that of a previously characterized, exclusively protoheme-containing, tetrameric catalase. 相似文献
64.
Inoculation of mature gerbils with BCG gave protection to subsequent infection with B. divergens when inoculated by the intracardiac and intraperitoneal routes, the latter showing a dose dependent relationship. BCG vaccination was most effective in immature gerbils (less than 4 weeks old), which are innately resistant to B. divergens. Vaccination of gerbils with killed Propionesbacterium acne and zymosan A failed to elicit a protective response, which contrasts conspicuously with rodent babesia studies. Incubation of B. divergens-infected gerbil blood with hydrogen peroxide produced parasite inhibition only at the highest concentration and treatment of parasitized gerbils with the oxidative radical inducer, alloxan monohydrate, gave equivocal results so it is evident that, unlike Plasmodium spp., B. divergens is not significantly susceptible to the action of reactive oxygen forms. 相似文献
65.
Monomorphism in humans and sequence differences among higher primates for a sequence tagged site (STS) in homeo box cluster 2 as assayed by denaturing gradient electrophoresis. 总被引:2,自引:2,他引:0
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G Ruano M R Gray T Miki A C Ferguson-Smith F H Ruddle K K Kidd 《Nucleic acids research》1990,18(5):1314
66.
Paul L. Wood Tadimeti S. Rao Smriti Iyengar Thomas Lanthorn Joseph Monahan Alex Cordi Eric Sun Michael Vazquez Nancy Gray Patricia Contreras 《Neurochemical research》1990,15(2):217-230
Conclusions Current neurochemical studies of the NMDA receptor macromolecular complex are yielding new insights into the interactions of the subunits of this complex and the associated potential clinical benefits of selective modulation of these subnits. Such studies offer the great potential for a new generation of pharmacotherapies for a wide range of CNS disorders, including stroke, a condition for which there is currently no effective pharmacological treatment. However, it is essential to understand that the first generation products in this area may not be optimal pharmacotherapies, such that haracterization of possible receptor subtypes and understanding the molecular biology of the component proteins of the receptor complex will be crucial in the design of the optimal pharmacological modulators of the NMDA receptor complex.Special issue dedicated to Dr. Erminio Costa 相似文献
67.
The nuchal ligament of unborn calves contains a neutral endopeptidase that is biochemically and immunologically similar to the neutral endopeptidase (NEP), or enkephalinase, from human kidney. Enzymatic activity was inhibited more than 90% by phosphoramidon (1 microM). The specific activity in membrane fractions, as determined by hydrolysis of the dansylated substrate, DAPGN, was similar in tissue from fetuses of gestational ages ranging from 100 to 280 days. NEP activity in adult ligament tissue, however, was less than 10% of that in fetal tissue. Fibroblasts dissociated from ligament tissue by collagenase displayed less NEP activity than did preparations of intact ligament, and activity was even lower in cultured cells. By contrast, fibroblasts cultured from fetal calf lungs had NEP activity comparable to that in the ligament tissue. When ligament fibroblasts were cultured on subcellular matrices derived from fetal lung fibroblasts the NEP activity increased relative to those cultured on plastic alone. These studies confirm the presence of neutral endopeptidase (NEP) in the nuchal ligament of the fetal calf. The consistent activity through a range of gestational ages and the influence of the subcellular matrix suggest that this enzyme might be involved in growth of the ligament during fetal life. 相似文献
68.
69.
Pascal Demange Salomé Wendenbaum Caroline Linget Christian Mertz Manh Thong Cung Anne Dell Mohamed A. Abdallah 《Biometals》1990,3(3-4):155-170
Summary In iron-deficient conditions,Pseudomonas aeruginosa ATCC 15692 synthesizes two major siderophores, pyoverdins Pa and pyoverdin Pa B. Two other compounds, pyoverdin Pa A (occurring from hydrolysis of pyoverdin Pa during the culture) and pyoverdin Pa C (occurring artifactually during the purification procedure) were also isolated. All these compounds possess the same partly cyclic peptide chain
wherel-Orn(OH · HCO) isN
-formyl,N
-hydroxy-l-ornithine. The chain is bound to a chromophore derived from 2,3-diamino-6,7-dihydroxyquinoline and having the (S) configuration. The four pyoverdins differ only in the acyl substituent bound to the nitrogen atom bound to carbon C3 of the chromophore. This is succinamide (pyoverdin Pa), succinic acid (pyoverdin Pa A), methyl succinate (pyoverdin Pa C) and 2-oxoglutaric acid (pyoverdin Pa B). The complete1H- and13CNMR assignments, using two-dimensional total correlation NMR spectroscopy (TOCSY) and rotating-frame Overhauser enhancement spectroscopy (ROESY) procedures, as well as1H-13C correlations, are reported. The complete sequence of the peptide using CH-NH correlations was achieved by NMR and confirmed the partly cyclic structure earlier reported using fast-atom-bombardment mass spectrometry (FAB-MS) on the siderophores and their dansylated fragments [Briskot G, Taraz K, Budzikiewicz H (1989)Liebigs Ann Chem: 375–384]. The use of these NMR procedures appears to be a tool of choice and a complementary approach to FAB-MS in the structure determination of some complex pyoverdins.Abbreviations Ser
serine
- Arg
arginine
- Thr
ethreonine
- Lys
lysine
- OHOrn
N
-hydroxyornithine
- Chr
chromophore 相似文献
70.
Identification of an amber nonsense mutation in the rosy516 gene by germline transformation of an amber suppressor tRNA gene. 总被引:7,自引:0,他引:7
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Seven xanthine dehydrogenase and cross-reacting material negative Drosophila melanogaster rosy stocks were screened for amber and ochre nonsense mutations. Amber and ochre nonsense suppressors were created by site-directed mutagenesis starting from a wild-type tRNA(Tyr) gene. The suppressor tRNA genes were subcloned into a pUChsneo transformation vector providing heat-shock controlled neomycin resistance. The seven rosy stocks were germline transformed with amber and ochre tDNA(Tyr), and the G1 generation was screened for Geneticin resistance. Surviving rosy516 flies transformed with the amber suppressor showed an eye colour intermediate between the original ry516 stock and the wild-type, suggesting that ry516 is an amber nonsense mutant. This was confirmed by sequencing the relevant part of the ry516 gene; the analysis revealed a C-to-T transition in a CAG glutamine codon at nucleotide 1522 of the wild-type rosy gene. 相似文献